GenStat BS3 / cleanup

A few more pages cleaned up - notable the depreciated `barcode_vs_expected.html` page, which now produces plots which can be read. Also several template pages which weren't being used for anything have been deleted.

Also a big cleanup in the `flowcell_samples.html` template - no manger change in functionality here, lots of reformatting the code so that I could read what was actually happening in the HTML (messy to review, sorry). Also changing some markup to use BS3 classes. **Change in functionality:** instead of showing "not found in DB" I've just hidden missing fields. Makes the page far smaller and easier to use I think. @Galithil - I'm pretty sure this will be going against what someone has asked you to do, sorry! Feel free to argue the point, or get me to pass it by any other interested people.

Phil
If it breaks, we fix it.. I'd rather have a field which people can read. I guess if I used a date class then it could be more resilient than using substrings, but I'd rather spend 2 minutes writing it and 2 minutes fixing it than 2 hours writing a system resilient to any and all format changes.